Implement Misses DSL compiler (parser + codegen)

- ast.rs: Full AST for .mrs files (MacroDef, Pattern, OutputBody, TemplateItem)
- parser.rs: Hand-written recursive descent parser with line/col error reporting
- codegen.rs: Transforms AST to Rust proc macro code using syn/quote/proc_macro2
- main.rs: CLI reads .mrs file, runs parse→codegen, writes to stdout or file
- Cargo.toml: Workspace with syn, quote, proc-macro2, prettyplease deps
- examples/: hello.mrs, derive_builder.mrs, declare_table.mrs reference examples

All three reference examples parse and produce prettyplease-formatted Rust output.
Generated code uses syn::parse::Parser closures for structural patterns, quote!
for token templates, spread iteration via .iter().map().collect(), and
format_ident! for identifier construction.

https://claude.ai/code/session_01Tppkab4eLsL21asHGjQJoF

misses-compiler/src/main.rs

@@ -0,0 +1,45 @@
+mod ast;
+mod parser;
+mod codegen;
+
+use std::path::PathBuf;
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() < 2 {
+        eprintln!("Usage: misses <input.mrs> [output.rs]");
+        std::process::exit(1);
+    }
+
+    let input_path = PathBuf::from(&args[1]);
+    let src = match std::fs::read_to_string(&input_path) {
+        Ok(s) => s,
+        Err(e) => {
+            eprintln!("Error reading {:?}: {}", input_path, e);
+            std::process::exit(1);
+        }
+    };
+
+    let ast = match parser::parse(&src) {
+        Ok(a) => a,
+        Err(e) => {
+            eprintln!("Parse error: {}", e);
+            std::process::exit(1);
+        }
+    };
+
+    let generated = codegen::codegen(&ast);
+
+    if args.len() >= 3 {
+        let output_path = PathBuf::from(&args[2]);
+        match std::fs::write(&output_path, &generated) {
+            Ok(_) => {}
+            Err(e) => {
+                eprintln!("Error writing {:?}: {}", output_path, e);
+                std::process::exit(1);
+            }
+        }
+    } else {
+        print!("{}", generated);
+    }
+}